The present invention relates in general to pulse width modulators and, more particularly, to pulse width modulator for performing voltage to duty cycle conversion.
Many circuit applications require signals to be transmitted over long distances and through noisy environments. In one example where a pressure sensor transducer monitors a pressurized system or other pressure source, the transducer converts pressure to an amplitude varying analog voltage signal. The analog signal is typically transmitted to a microcontroller to process the pressure status and possibly make appropriate adjustments to the system. The microcontroller may be located some distance from the pressure sensor, or possibly in a noisy industrial environment. Consequently, the analog signal is often subject to noise interference which can effect its instantaneous amplitude. Any noise introduced onto the analog signal creates misrepresentations of the actual pressure thereby causing the microcontroller to mis-report or mis-correct the system.
A common solution has been to use a voltage controlled oscillator to convert the amplitude varying analog signal into a frequency varying signal. The frequency varying signal is much less subject to common low frequency noise in the industrial setting. Filters may be used at the receiving end to remove any low frequency noise. Most microcontrollers are digital in nature thereby requiring the frequency varying signal to be converted to digital form before use. However for good performance, the transducer voltage to frequency conversion circuitry tends to be complex and expensive.
Hence, a need exists to convert an analog signal to a form that is robust to noisy transmission while requiring minimal re-conversion before end use.